Cerebellum (the "little brain" beneath the cerebrum)
Brain Stem (connects to the spinal cord)
The cerebrum is divided into two hemispheres (left & right).
Functions of the Cerebral Hemispheres
Primary Motor and Sensory Cortices:
Located in the outer layer (cortex) of the cerebrum.
Gray Matter: Site of neuron cell bodies and synapsing (integration of information).
White Matter: Axons surrounded by myelin (signal highways).
Primary Motor Cortex
Located in the frontal lobe.
Initiates voluntary or conscious motor movement (e.g., walking).
Sensory Cortex
Information from external or internal environment reaches here for conscious awareness (e.g., feeling objects).
Association Areas
Assist primary cortices by integrating current and previous information.
Motor Association Areas: Plan and sequence complex tasks (e.g., playing piano).
Sensory Association Areas: Analyze sensory information (e.g., texture, temperature).
Conscious Experience and Limbic System
Cortex: Essential for conscious awareness (1-5 mm thick layer).
Limbic System: Involved in memory and emotional aspects of behavior (e.g., relationships, fight or flight).
Cognitive Functions
Prefrontal Cortex: Located in the frontal lobe, crucial for planning, judgment, and appropriate behavior.
Damage can affect behavior and planning abilities.
Structure of the Cerebral Hemispheres
Gray Matter: Site of consciousness and integration.
White Matter: Comprises fibers connecting different brain regions.
Commissural Fibers: Connect the two hemispheres via the corpus callosum.
Projection Fibers: Connect cortex with deeper brain regions and spinal cord.
Association Fibers: Connect different parts of the cortex within the same hemisphere.
Lobes of the Cerebral Hemisphere
Frontal Lobe
Parietal Lobe
Occipital Lobe
Temporal Lobe
Insular Lobe: Hidden beneath the frontal and temporal lobes.
Surface Anatomy
Gyri (singular: Gyrus): Raised areas or folds.
Sulci (singular: Sulcus): Grooves or depressions.
Important Sulci:
Central Sulcus: Separates frontal from parietal lobe.
Parieto-occipital Sulcus: Separates parietal from occipital lobe.
Lateral Sulcus (Sylvian Fissure): Separates temporal from frontal and parietal lobes.
Conclusion
The cerebral hemispheres are the largest, most complex parts of the brain, responsible for consciousness, cognitive function, emotion, and integration of sensory and motor information. Future lectures will delve deeper into each lobe's specific roles and functions.